The Central Laboratory (CL) of the HIV Vaccine Trials Network (HVTN) is constituted by 3 highly experienced Core Laboratories (CoL) that perform state of the art virological and immunological assays that support Phase I/II clinical trials in the U.S. and at several international sites. Complementing the Core studies is a network of 12 collaborating laboratories designated Scientific Emphasis Groups (SEG) that conduct cutting edge developmental research on various topics that are pertinent to the vaccine trials. These include broad areas such as pathogenesis, viral variation host variation, humoral, cellular and mucosal responses to vaccines and viral suppression. An additional SEG will serve to provide a strong linkage between vaccine trials in humans and cognate studies in the non-human primate model. In addition the CL and the HVTN have established a process whereby linkages to the broader scientific community can occur through provision of materials and reagents emanating from the vaccine trials as well as funding for meritorious studies. The CL includes administrative, organizational and management structures that ensure effective communication within the laboratory network as well as between the CL and various functional units of the HVTN.